It has been very desirable to achieve new and unique visuals in floor covering products, and many end-users find it desirable to heat weld flooring seams in an effort to prevent dirt and bacteria from entering the seams. One such method has been to heat weld seams with a solid-colored welding rod. This has become a popular practice in the healthcare industry where sanitation requirements are extremely important.
Not only have flooring manufacturers provided welding rods for seam sealing, but many wall systems are also being marketed with seam welding or seam sealing materials. The end users and job specifiers also often employ seam welding rods as an option to offer a decorative styling element to the specified job. They can add a solid colored welding rod that compliments the color of the patterned floor, or they can use an "accent" color that contrasts sharply with the floor to create a bold new look.
Only recently, however, has a manufacturer offered a non-solid, colored heat welding rod. The welding rod is a through-colored, patterned welding rod which matches the color and design of the floor covering pattern. This heat welding rod uses methods which create a through-color visual which extends all the way from the surface down through the entire depth of the composition in an uninterrupted fashion. The pattern is limited to a multi-colored, chip- or granule-image. Prior to the present invention, a welding rod having a distinct, repeatable pattern has not been produced.
The use of an extruded, solid colored or clear, polyvinyl chloride, round cross-section welding rod is well known in the art to join two pieces of vinyl resilient flooring together. This prior art process uses an unfilled, highly plasticized, colored polyvinyl chloride formulation that is in turn extruded through a round die to form a round cross-section, flexible, easily cut rod for seam sealing.
Extrusion yields a solid color rod or, in some cases in which there are shade variations, a swirl effect such as a barber pole results. In no instance is a distinct sharp edge design obtained. The solid color rod areas appear as a seam of solid contrasting color at every welded installation site creating a discontinuity in the flooring surface. This disrupts the flooring pattern image. The desire for a single image flooring or a flooring surface wider than the width of the flooring product, but having a continuous image has been expressed by many designers and architects. No known welding rod containing a distinct pattern is known.